Final answer:
Microscopic molecules of DNA become visible as chromosomes under a light microscope during cell division because they condense and replicate, allowing them to be seen when the nucleus breaks down.
Step-by-step explanation:
During the cell cycle, cells undergo various stages, including interphase (G1, S, and G2 phases) followed by mitosis or meiosis, where DNA replication and cell division occur.
Before cell division, during the prophase stage of mitosis or meiosis, DNA undergoes a process called condensation. The chromatin, which is the loosely packed DNA-protein complex during interphase, condenses into tightly coiled structures known as chromosomes. This condensation process is crucial for several reasons:
Visibility under light microscope: The condensation of DNA into chromosomes makes them visible under a light microscope. In their condensed state, chromosomes are easier to distinguish and observe due to their compacted and organized structure.
Facilitating segregation: Condensation of DNA into visible chromosomes aids in the orderly segregation of genetic material during cell division. The condensed chromosomes ensure that genetic material is properly distributed between daughter cells.
Preventing entanglement: Condensation helps prevent DNA from becoming entangled and aids in the efficient movement and distribution of chromosomes to daughter cells.
Overall, the condensation of DNA into visible chromosomes just prior to and during cell division is essential for accurate segregation, ensuring that genetic material is equally distributed to daughter cells and facilitating the observation and study of cellular processes using light microscopy.